CHAPTER 13 Spectroscopy
What three-word term is abbreviated NMR? - correct answer-Answer: nuclear magnetic
resonance
A nucleus with an __________ atomic number or an __________ mass number has a
nuclear spin that can be observed by the NMR spectrometer.
A) even, odd
B) odd, even
C) odd, odd
D) even, even - correct answer-C
How many nuclear spin states are allowed for the 1H nucleus?
A) 1
B) 2
C) 3
D) 4
E) 10 - correct answer-B
The energy difference between the allowed spin states for an 1H nucleus is __________ the
strength of the external magnetic field in which it is placed.
A) independent of
B) directly proportional to
C) inversely proportional to
D) exponentially related to
E) logarithmically related to - correct answer-B
Calculate the magnetic field that corresponds to the proton resonance frequency of 300.00
MHz. The gyromagnetic ratio of the 1H nucleus is 26,753 s-1 gauss-1. - correct
answer-70,458 gauss
6) 1H nuclei located near electronegative atoms tend to be __________ relative to 1H nuclei
which are not.
A) shielded
B) deshielded
C) resonanced
D) split - correct answer-B
Electromagnetic radiation in the __________ region is used in 1H NMR spectroscopy.
A) radio wave
B) ultraviolet
C) infrared
D) microwave
E) X-ray - correct answer-A
, If a molecule contains 4 elements of unsaturation and signals in the 1H NMR spectrum
between δ 7.0 and 8.0 ppm, what structural group is likely to be present?
A) a carbonyl group
B) an aromatic ring
C) a hydroxyl group
D) a cyclohexyl ring
E) a carbon-carbon triple bond - correct answer-B
Which of the following functional groups has the most deshielded proton and would be
predicted to show an NMR signal that is the farthest downfield?
A) benzylic - H
B) allylic - H
C) aldehyde - H
D) aromatic - H
E) acetylenic - H - correct answer-C
10) Using a 60-MHz spectrometer, the protons in dichloromethane appear at 5.30 ppm.
When the same sample is placed in a 100-MHz instrument, where does the signal appear?
A) 8.33
B) 5.30
C) 3.18 - correct answer-B
__________ is commonly used as an internal reference in NMR spectroscopy; its signal is
assigned d = 0 in 1H and 13C NMR spectroscopy. - correct answer-Answer:
Tetramethylsilane, (CH3)4Si
On a 90 MHz spectrometer, calculate the frequency at which a proton absorbs if it appears
at 4.20 ppm. - correct answer-Answer: 378 Hz
Predict the number of signals expected (disregarding splitting) in the 1H spectrum of
m-xylene (1,3-dimethylbenzene). - correct answer-4
) Predict the number of signals expected (disregarding splitting) in the 1H spectrum of
o-chlorophenol (2-chlorophenol). - correct answer-5
Predict the number of signals expected (disregarding splitting) in the 1H spectrum of dibutyl
ether. - correct answer-4
Predict the number of signals expected (disregarding splitting) in the 1H spectrum of
1,1-dimethylcyclobutane. - correct answer-C
A compound (C5H8O) shows IR absorptions at 3600 and 3300 cm-1. Its 1HNMR spectrum
contained singlets at δ 1.5, 2.2, and 2.9 (broad) (ppm) in a ratio of 6:1:1. Name this
compound. - correct answer-2-methylbut-3-yn-2-ol
What is the relative area of each peak in a quartet spin-spin splitting pattern?
What three-word term is abbreviated NMR? - correct answer-Answer: nuclear magnetic
resonance
A nucleus with an __________ atomic number or an __________ mass number has a
nuclear spin that can be observed by the NMR spectrometer.
A) even, odd
B) odd, even
C) odd, odd
D) even, even - correct answer-C
How many nuclear spin states are allowed for the 1H nucleus?
A) 1
B) 2
C) 3
D) 4
E) 10 - correct answer-B
The energy difference between the allowed spin states for an 1H nucleus is __________ the
strength of the external magnetic field in which it is placed.
A) independent of
B) directly proportional to
C) inversely proportional to
D) exponentially related to
E) logarithmically related to - correct answer-B
Calculate the magnetic field that corresponds to the proton resonance frequency of 300.00
MHz. The gyromagnetic ratio of the 1H nucleus is 26,753 s-1 gauss-1. - correct
answer-70,458 gauss
6) 1H nuclei located near electronegative atoms tend to be __________ relative to 1H nuclei
which are not.
A) shielded
B) deshielded
C) resonanced
D) split - correct answer-B
Electromagnetic radiation in the __________ region is used in 1H NMR spectroscopy.
A) radio wave
B) ultraviolet
C) infrared
D) microwave
E) X-ray - correct answer-A
, If a molecule contains 4 elements of unsaturation and signals in the 1H NMR spectrum
between δ 7.0 and 8.0 ppm, what structural group is likely to be present?
A) a carbonyl group
B) an aromatic ring
C) a hydroxyl group
D) a cyclohexyl ring
E) a carbon-carbon triple bond - correct answer-B
Which of the following functional groups has the most deshielded proton and would be
predicted to show an NMR signal that is the farthest downfield?
A) benzylic - H
B) allylic - H
C) aldehyde - H
D) aromatic - H
E) acetylenic - H - correct answer-C
10) Using a 60-MHz spectrometer, the protons in dichloromethane appear at 5.30 ppm.
When the same sample is placed in a 100-MHz instrument, where does the signal appear?
A) 8.33
B) 5.30
C) 3.18 - correct answer-B
__________ is commonly used as an internal reference in NMR spectroscopy; its signal is
assigned d = 0 in 1H and 13C NMR spectroscopy. - correct answer-Answer:
Tetramethylsilane, (CH3)4Si
On a 90 MHz spectrometer, calculate the frequency at which a proton absorbs if it appears
at 4.20 ppm. - correct answer-Answer: 378 Hz
Predict the number of signals expected (disregarding splitting) in the 1H spectrum of
m-xylene (1,3-dimethylbenzene). - correct answer-4
) Predict the number of signals expected (disregarding splitting) in the 1H spectrum of
o-chlorophenol (2-chlorophenol). - correct answer-5
Predict the number of signals expected (disregarding splitting) in the 1H spectrum of dibutyl
ether. - correct answer-4
Predict the number of signals expected (disregarding splitting) in the 1H spectrum of
1,1-dimethylcyclobutane. - correct answer-C
A compound (C5H8O) shows IR absorptions at 3600 and 3300 cm-1. Its 1HNMR spectrum
contained singlets at δ 1.5, 2.2, and 2.9 (broad) (ppm) in a ratio of 6:1:1. Name this
compound. - correct answer-2-methylbut-3-yn-2-ol
What is the relative area of each peak in a quartet spin-spin splitting pattern?
